[GHC] #13378: ghc-stage2 broken for quick-llvm

[GHC]

#13378: ghc-stage2 broken for quick-llvm
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        Reporter:  angerman          |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Compiler          |              Version:
      Resolution:                    |             Keywords:
Operating System:  MacOS X           |         Architecture:  x86_64
 Type of failure:  Building GHC      |  (amd64)
  failed                             |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by rwbarton):

 * priority:  highest => normal
 * status:  patch => new
 * differential:  Phab:D3290 =>
 * milestone:  8.2.1 => 8.4.1


Comment:

 Commit 1686f30951292e94bf3076ce8b3eafb0bcbba91d made the mangler remove
 `.subsections_via_symbols` from LLVM output, implementing option 1 above.
 So the current status is that the LLVM backend works fine; there just
 isn't any way to get dead code stripped from modules built by the LLVM
 backend.

 `-split-objs` never worked with LLVM anyways, so this is not a regression.
 So no need to revert the other splitter-related changes.

 For the most part the LLVM backend is only used for end-user code, rather
 than for libraries. So there isn't likely to be much dead code to strip
 anyways. But for targets like iOS on arm/aarch64, LLVM is the only backend
 option; so I'm leaving this ticket open.

 Unfortunately the approach using `.alt_entry` did not quite work out, for
 reasons that are not entirely clear.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13378#comment:8>
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